Push technology (aka “server push”) is a type of internet-based communication where the request for a given transaction is initiated by a “publisher” or server. It is contrasted with pull technology where the request for transmission of information is initiated by a receiving device or “client.”
Push services are sometimes based upon information preferences expressed in advance. This is referred to as a “publish/subscribe” model. For example, a client might subscribe to one or more information “channels.” The server associated with the channels can then push information to the client when new content becomes available.
There are many types of push services. For example, synchronous conferencing and instant messaging are forms of push services. Increasingly popular are push-enabled web applications including market data distribution (e.g. stock tickers), online chat/messaging systems (e.g. “webchat”), auctions, online betting and gambling, sports results, monitoring consoles and sensor network monitor.
There are also hybrid push/pull systems. For example, email begins as a push system in that the SMTP protocol upon which it is based is a push protocol. However, the last step in the delivery of an email, e.g. from a mail server to a desktop computer, typically uses a pull protocol such as POP3 or IMAP.
As will be appreciated, there are many and widespread uses for push technology. However, one drawback of such technology is that it is, essentially, a unidirectional technology where pushes are sent to devices and then forgotten. This limits the opportunity to improve the effectiveness of future pushes by deriving feedback as to the effectiveness of prior pushes.